This invention relates to an electro-optical device including non-linear metal-insulator-metal (MIM) devices arranged in a matrix and more particularly, to a MIM device wherein the second metal film layer is completely covered by a transparent picture cell electrode.
Liquid crystal display devices have application in many fields, especially in watches, electronic calculators and other portable electronic devices. Such devices employ various type display units to be driven at low voltages, thus requiring low power consumption. However, when such devices are employed in information display terminals or small hand-held electronic equipment, there are disadvantages. Such devices yield an image with relatively poor contrast regardless of the level of driving voltage. In addition, resolution and capacity of display information is limited due to the inability to drive the display in a multiplex mode.
In order to eliminate such disadvantages and increase the amount of information that can be shown, non-linear elements, such as MIM's, may be used in liquid crystal display devices. Prior art MIM elements are constructed by anodizing the surface of a Ta film pattern and forming a Cr pattern thereon. By such construction, a MIM element is formed by layering in the vertical direction at the junction of the overlapping Ta pattern and Cr pattern. In the conventional process for manufacturing such a MIM element, it was necessary to form a first metal film, a second metal film and a transparent picture cell electrode by different photolithographic steps. This was needed in order to construct the various components. The result was a low yield and increase in production costs.
Accordingly, it is desirable to provide a new MIM device and electro-optical devices including the MIM which overcomes the problems of the prior art outlined above.